John Arnold was an attacking opening batsman for Hampshire for 20 years from 1930, when he qualified by residence, having previously played Minor Counties cricket for Oxfordshire. He scored 1,000 runs in his first full first-class season and missed out on that feat only once in his career. In 1934, he scored 2,261 runs at an average of 48 runs per innings, the only time he passed 2,000 runs in a season. His one poor season, 1938, led to him not being re-engaged by Hampshire, but the county had second thoughts and he returned for the 1939 season and for five more seasons after the Second World War. He fell ill during the 1950 season, and retired without playing again. He was a first-class umpire for 14 seasons from 1961.

Arnold played only one Test match: with Fred Bakewell, he formed an experimental opening partnership for England against New Zealand at Lord's in 1931, following the retirement from Test cricket of Jack Hobbs and injury to Herbert Sutcliffe. The move was not a success. Arnold was out for 0 in the first innings, and though he scored 34 in the second, he was replaced by the returning Sutcliffe for the second Test. He did not play Test cricket again.